I'm having a very strange problem... I uploaded some parts earlier today and they worked fine.

I went to upload some more parts just now and shapeways takes them as meters rather than mm. I checked my models and they are correct, I checked the .stl settings when I save and that is set to mm, I checked the shapeways drop down menu is set to mm and yet still it comes back and uploads in meters!

No idea what's going on.... first time I've had this problem and I've uploaded many many models previously.

EDIT - and I just updated a couple of models that previously updated fine - I get a note saying they were too big at the meter scale and have been changed to mm. Something is screwy for sure, but is it only me?

Yes same issue here. Updating a previous model works fine though.
So I guess the work-around is to upload a very small model like a cube of 0.01x0.01x0.01mm and then to update it with the correct model.
Or you can wait for the bug to be fixed...

in my program when exporting my model as an .STL I can click options, then set the desired resoution settings and scale to mm etc.

I'm not sure it's strictly relevant, as it's still just "units" and if you choose inches when you upload then it'd end up in displaying those units as inches... but the option is there.

Anyway, since it's not just me clearly there's a bug in the shapeways system at the moment. For the record I'm still having issues with uploaded models but updating existing models appears to be working.

STL files don't have units -- they contain only triangles, there's no place to put anything else -- so any software that claims it's saving an STL "as" a certain unit is lying. STL units are set at upload time, not at save time.

That's why you have to tick the mm/inches/meters box when you upload to Shapeways: otherwise it truly has no way to know the size, because there are no units in the file.

I too uploaded earlier today and it was fine, it's only since this afternoon that I've experienced trouble. The units selected when I upload are 100% for certain mm, but it then tells me it was too large so has been changed from meters to mm/inches depending on the model.

Using both OSX with safari and Windows 7 with IE. Scale is selected as mm from the drop down menu but it ends up trying to do it in meters, model is too big and ends up in inches.

This particular model is 20 "units" in diameter, as you can see from the link shapeways ends up making it 20 inches despite my selection of mm from the drop down menu when I upload. On other models that are bigger it changes the scale from meters to mm and ends up correct by an incorrect means.... like I say this problem only started for me on sunday afternoon - previously I never had a problem.

Your model was too big for the printer when using the meter scale
However, we scaled your model using the inches scale, now your model at 20.0 x 20.0 x 5.0 inches, or 50.80 x 50.80 x 12.70 cm can be printed!
If this is not the scale you intended, please rescale your model and re-upload."

By first uploading a part that gets converted by shapeways from meters to mm and then updating the file with the actual desired model I end up with a correctly scaled model....

as I say though it isn't just this model, it's every model I've tried to upload since sunday.... including ones that previously uploaded fine. I confirmed it by uploading another .stl from a few weeks ago which worked fine the first time I uploaded it back then and the same happens.